||~ 1.4 eV (indirect)
||Vanadium selenide, Bis(selanylidene)vanadium
|Classification / Family
Transition metal dichalcogenides (TMDCs), 2D Semiconductor Materials, Charge Density Wave (CDW), Hydrogen Revolution Reactions (HER), Nano-electronics, Nano-photonics, Photovoltaic, Materials science
||Synthetic - chemical vapour transport (CVT)
Vanadium diselenide (VSe2) is a typical TMDC material. With a sandwiched layer structure, its layers are bound by weak van de Waals forces which allow the isolation of each layer from its bulk crystals (or powder) to reduce the dimensionality - by either mechanical or chemical exfoliation.
In bulk form VSe2 is paramagnetic. It commonly condenses in the 1T structure, which is metallic with no optical bandgap. Monolayer VSe2 has magnetic characteristics and a lower work-function at its edge. However, strong room-temperature ferromagnetism was observed in VSe2 monolayers grown on van der Waals substrates (such as graphite). 
Vanadium diselenide has great potential as a catalyst or electrode material in electrochemical hydrogen evolution reaction (HER), supercapacitors, photocatalytic and photoelectrochemical reactions, and lithium-ion and sodium-ion batteries.
Vanadium diselenide powder is obtained via the CVT method, with a purity in excess of 99.995% achieved.
Vanadium diselenide powder is suitable for liquid chemical exfoliation to prepare VSe2 nanosheets and nanoparticles down to few-layer films. 2D VSe2 nanosheets (NSs) can be successfully produced via an ultrasonication-assisted lithium intercalation process using lithium carbonate in a colloidal solution of NPs. VSe2 powder is also used for the preparation of mono-layer and few-layer films via chemical vapour deposition (CVD).
Literature and Reviews
- Strong room-temperature ferromagnetism in VSe2 monolayers on van der Waals substrates, M. Bonilla et al., Nat.Nanotech., 13, 289–293 (2018); DIO: 10.1038/s41565-018-0063-9.
Thickness dependence of the chargedensity-wave transition temperature in VSe2, J. Yang et al., Appl. Phys. Lett. 105, 063109 (2014); DIO: 10.1063/1.4893027.
Strain and interlayer coupling tailored magnetic properties and valley splitting in layered ferrovalley 2H-VSe2, S. Feng et al., Appl. Surf. Sci., 458, 191–197 (2018); DIO: 10.1016/j.apsusc.2018.07.070.
Epitaxially grown monolayer VSe2: an air-stable magnetic two-dimensional material with low work function at edges, Z. Liu et al., Sci. Bull., 63, 419–425 (2018); DIO: 10.1016/j.scib.2018.03.008.
Intrinsic valley polarization of magnetic VSe2 monolayers, J. Liu et al., J. Phys.: Condens. Matter, 29, 255501 (2017); DIO: 10.1088/1361-648X/aa6e6e.
Dimensional crossover of the charge density wave transition in thin exfoliated VSe2, A. Pásztor et al., 2D Mater., 4, 041005 (2017); DIO: 10.1088/2053-1583/aa86de.
Metallic Graphene-Like VSe2 Ultrathin Nanosheets: Superior Potassium-Ion Storage and Their Working Mechanism, C. Yang et al., Adv. Mater., 30, 1800036 (2018); DOI: 10.1002/adma.201800036.
Catalytic Properties of Vanadium Diselenide: A Comprehensive Study on Its Electrocatalytic Performance in Alkaline, Neutral, and Acidic Media, T. Ghobadi et al., ACS Omega, 2, 8319−8329 (2017); DOI: 10.1021/acsomega.7b01226.